Same, this happens every time I launch Arena. I'm using Win 10. Screenshot attached.

i have had this problem since zendikar came out

Same here since the zendikar update, wotc please fix, if so many of us have the same issue, the problem is not our computer or network, it's MTGA.

Same issue since Zendikar update. Reinstalled no change. Does not matter what I play or how long.

same here. after a reinstallation it got better but it still happens occasionally.

Update. After putting computer to sleep (Arena not running) and waking it up, the delete AssetBundle contents solution stopped working, and asset error returned.

i re installed and still happens to me.

Same error, every log in I have to wait while it checks assets.

Same error, every login.

I have reinstalled twice now to try to fix and it wont stop happening

Got frustrated with this. Found a solution that worked for me. Went to:
C:\Program Files\Wizards of the Coast\MTGA\MTGA_Data\Downloads
Deleted the Manifest_etc.. and everything in the AssetBundle folder.

Also, to reduce hanging and crashing, I force-quit the unity crash handler.

Same situation at every start up of the game. This has been happening ever since the Zendicar update.

every time I log into MTG arena it takes 10 minutes to go through an asset error occured check.

This is ridiculous.

Still happening, rather annoying to lose draft matches because of this.

I won't say I was winning, it was too early for that, but I had a good shot and got disconnected and with this 'validating assets' ****, getting DCed means losing.

That needs to change for me to feel confident spending even a single euro on this game.

Same error, every login. I even tried to reinstall

I got an "Asset Error Validation" error during the Ikoria Quick Draft, causing me to lose a match due to a timeout. This error has occurred to me repeatedly, but this is the first time it has costed me a loss during an event I paid gems for.

I have this error since the rotation, but haven't played the game for a while. Every time I log in I need 2-5 minutes more.

Same for me, it's a shame that such serious issue is ignored more than for a month

I'm also having this issue repeatedly. Importantly, my game is crashing in the middle of drafts or sealed matches which is giving me losses that cost me gems. This has only been happening since the update to ZNR. Get your **** together!

same situation.
not solved by any update so far.
The 10 minutes of checking process also requires a lot of resources.